Photographic silver halide emulsions sensitized with 1, 1-dimethylhydrazinium salts



United States Patent PHQTOGRAPHIC SSHLVER HALIDE EMULSHUNS dENSlTIZED WITH Ll-DEMETHYLHYDRAZHNJI- UM SALTS Delbert D. Reynolds, Rochester, N.Y., and Ruth M. Stewart, Laurel, Md, assignors ta Eastman Kodak Company, Rochester, N.Y., a corporation of New .lersey No Drawing. Filed July 13, 1961, Ser. No. 124,800

12 Claims. (Cl. 96-467) This invention concerns photographic silver halide emulsions, and more particularly, photographic silver halide emulsions containing novel sensitizing addenda.

It is well known in the photographic art that silver halide emulsions can be chemically sensitized with a variety of materials in order to increase their speed. Certain chemical sensitizers are believed to react with the silver halide to form on the surface of the silver halide minute amounts of silver sulfide, or of silver, or of other noble metals. In addition, other classes of compounds can be utilized to increase the sensitivity of photographic silver halide emulsions that apparently do not enter into chemical combination with the silver halide. Such sensitization reaches a limit beyond which further addition of sensitizer merely increases the fog of the photographic emulsion with constant or decreasing speed.

It is an object of this invention to provide novel photographic silver halide emulsions that have increased sensitivity.

It is another object of this invention to substantially increase the speed of photographic silver halide emulsions without increasing fog to objectionable levels.

These and other objects of the invention are accomplished by incorporating into photographic silver halide emulsions sensitizing amounts of 1,1-dimethylhydrazinium salts.

The 1,1-dimethylhydrazinium salts of the invention are 1 alkyl-1,l-dimethylhydrazinium salts and a,w-alkylene bis(1,1-dimethylhydrazinium salts) having the formulas H a a wherein R is an alkyl radical generally having 2 to 20 carbon atoms and preferably 5 to 20 carbon atoms, R is an alkylene radical generally having 2 to 20 carbon atoms and preferably 2 to 12 carbon atoms, and X is an anion. Typical alkyl substituents for R include ethyl, isopropyl, n-butyl, isobutyl, n-hexyl, Z-ethylhexyl, n-decyl, n-dodecyl, n-hexadecyl, n-octadecyl, eicosyl, and the like. Typical alkylene substituents for R include ethylene, trimethylene, tert.-butylene, tetramethylene, hexamethylene, decamethylene, tetradecamethylene, hexadecamethylene, octadecamethylene, and the like. Typical anion substituents for X include p-toluene sulfonate, perchlorate, chloride, and the like ions.

The subject unique substituted hydrazinium salts are characterized as having a nitrogen-to-nitrogen linkage with one of the nitrogen atoms being tetra covalent and having the structure,

A wide variety of such hydrazinium salts including such la-lkyl-1,1-dimethyll1ydraziniuin salts as;

l-ethyl-l,l-dimethylhydraziniurn perchlorate, l-n-butyl-l,l-dimethylhydrazinium p-toluene sulfonate, l-isobutyl-1,1-dimethylhydrazinium perchlorate, l-n-pentyl-l,l-dimethylhydrazinium perchlorate,

l-n-octyl-1,l-dimethylhydrazinium p-toluene sulfonate, l-n-decyl-1,1-dimethylhydrazinium perchlorate, l-n-d'odecyl-1,1-dimethylhydrazinium perchlorate, l-n-tetradecyl-l,l-dimethylhydrazinium chloride, l-n-hexadecyl-l,l-dimethylhydrazinium perchlorate, l-n-octadecyl-1,1-dimethylhydrazinium perchlorate, l-eicosyl-1,l-dimethylhydrazinium p-toluene sulfonate,

and the like; and such a,w-alkylene bis(1,1-dimethylhydrazinium salts) as;

l,2-ethylene bis(1,l-dimethylhydrazinium ptoluene sulfonate),

1,4-tetramethylene bis(1,1-dimethylhydrazinium perchlorate),

1,6-hexamethylene bis(1,1-dimethylhydrazinium perchlorate),

1,8-octamethyl6ne bis(1,1-dimethylhydrazinium chloride),

1,10-decamethylene bis(1,1-dimethylhydrazinium perchlorate),

1,12-dodecamethylene bis 1,1-dimethylenehydrazinium p-toluene sulfonate),

1,14-tetradecamethylene bis l,1-dimethylenehydrazinium perchlorate) 1 ,18octadecamethylene bis 1, l-dimethylenehydrazinium perchlorate), and the like.

The present 1,1-dimethylhydrazinium salts are added to photographic silver halide emulsions in conventional sensitizing amounts in accordance with usual practice. Generally, however, about .01 to 10 and preferably about .1 to 5 grams per mole of silver halide in the emulsion of the 1,1-dimethylhydrazinium salts are utilized.

The preparation of photographic silver halide emulsions such as are used with the addenda of this invention involves three separate operations: (1) emulsification and digestion of silver halide, (2) the freeing of the emulsion of excess water-soluble salts, suitably by washing with water, and (3) the second digestion or afterripening to obtain increased emulsion speed or sensitivity. (Mees, The Theory of the Photographic Process, 1954.) The addenda of the invention can be added to the emulsion before the final digestion or after-ripening, or they can be added immediately prior to the coatmg.

The addenda or" the invention can be added to photographic emulsions using any of the well-known techniques in emulsion making. For example, they can be dissolved in a suitable solvent and added to the silver halide emulsion, or they can be added to the emulsion in the form of a dispersion similar to the technique used to incorporate certain types of color-forming compounds (couplers) in a photographic emulsion. Techniques of this type are described in Jelley et al. U.S. Patent 2,322,- 027, issued June 15, 1943, and Fierke et al. US. Patent 2,801,171, issued July 30, 1957. The solvent should be selected so that it has no harmful effect upon the emulsion in accordance with usual practice, and generally solvents or diluents which are miscible with water are to be preferred.

The emulsions can be digested with naturally active gelatin, or sulfur compounds can be added, such as those described in Sheppard U.S. Patent 1,574,944, issued March 2, 1926, and Sheppard et al. 1,623,499, issued April 5, 1927, and Sheppard and Brigham US. Patent 2,410,689, issued November 5, 1946. The emulsions can also be treated with salts of the noble metals such as ruthenium, rhodium, palladium, iridium and platinum. Representative compounds are ammonium chloropalladate, potassium chloroplatinate, and sodium chloropalladite, which are used in arnountsbelow that which produces any substantial fog inhibition, as described in Smith and Trivelli US. Patent 2,448,060, issued August 31, 1948, and as antifoggants in higher amounts, as described in Trivelli and Smith US. Patents 2,566,245, issued August 28, 1951 and 2,566,263, issued August 28, 1951. The emulsions can also contain small amounts of gold salts as described in Waller et al. US. Patent 2,399,083, issued April 23, 1946, or in Damschroder US. Patent 2,597,856, issued May 27, 1952, and Yutzy and Leermakers US. Patent 2,597,915, issued May 27, 1952. Suitable compounds are potassium ehloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride and 2-aurosulfobenzothiazole methochloride. The emulsions can also contain small amounts of reducing agents such as stannous salts (Carroll US. Patent 2,487,850, issued November 15, 1949), polyamines, such as diethylene triamine (Lowe and Jones US. Patent 2,518,698, issued August 15, 1950), polyamines, such as spermine (Lowe and Allen US. l-atent 2,521,925, issued September 12, 1950), or bis(fi-aminoethyl)sulfide and its water-soluble salts (Lowe and Jones US. Patent 2,521,926, issued September 12, 1950).

The emulsions can also be optically sensitized with cyanine and merocyanine dyes, such as those described in Brooker US. Patents 1,846,301, issued February 23, 1932; 1,846,302 issued February 23, 1932; and 1,942,854, issued January 9, 1934; White US. Patent 1,990,507, issued February 12, 1935; Brooker and White US. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747, issued January 10, 1950; and 2,739,964, issued March 27, 1956; Brooker and Keyes US. Patent 2,493,748, issued January 10, 1950; Sprague US. Patents 2,503,776, issued April 11, 1950 and 2,519,- 001, issued August 15, 1950; Heseltine and Brooker US. Patent 2,666,761, issued January 19, 1954; Heseltine US. Patent 2,734,900, issued February 14, 1956; Van

'Lare U.S. Patent 2,739,149, issued March 20, 1956; and

Kodak Limited British Patent 450,958, accepted July 15, 1936.

The emulsions can contain a suitable gelatin plasticizer such as glycerin; a dihydroxy alkane such as 1,5- pentanediol as described in Milton and Murray US.

'Patent 2,960,404, issued November 15, 1960; an ester of an ethylene bis-glycolic acid such as ethylene bis (methyl glycolate) as described in Milton U.S. Patent 2,904,434, issued September 15, 1959; bis(ethoxy diethylene glycol)succinate as described in Gray US. Patent 2,940,854, issued June 14, 1960, or a polymeric hydrosol as results from the emulsion polymerization of a mixture of an amide of an acid of the acrylic acid series, an acrylic acid ester and a styrene-type compound as described in Tong US. Patent 2,852,386 issued September 16, 1958. The plasticizer may be added to the emulsion before or after the addition of a sensitizing dye, it used.

The emulsions can be hardened with any suitable hardener for gelatin such as formaldehyde; a halogensubstituted aliphatic acid such as mucobromic acid as described in White US. Patent 2,080,019, issued May 11, 1937; a compound having a plurality of acid anhydride groups such as 7,8-diphenylbicyclo(2,2,2)-7-octene- 2,3,5,6-tetracarboxylic dianhydride, or a dicarboxylic or a disulfonic acid chloride such as terephthaloyl chloride or naphthalene1,5-disulfonyl chloride as described in Allen and Carroll U.S. Patents 2,725,294 and 2,725,295, both issued November 29, 1955; a cyclic 1,2-diketone such as cyclopentane-1,2-dione as described in Allen and Byers US. Patent 2,725,305, issued November '29, 1955; a bisester of methane-sulfonic acid such as 1,2-di-(methanesultonoxy) ethane as described in Allen and Laakso US. Patent 2,726,162, issued December 6, 1955', 1,3-dihydroxymethylbenzimidazol-2-one as described in July, Knott and Pollak US. Patent 2,732,316, issued Janumy 24, 1956; a dialdehyde or a sodium bisulfite derivative thereof, the aldehyde groups of which are separated by 23 carbon atoms, such as fl-methylglutaraldehyde t halide emulsion layer.

4 bis-sodium bisulfite; a bisaziridine carboxamide such as trimethylene bis(1-aziridine carboxamide) as described in Allen and Webster US. Fatent 2,950,197, issued August 23, 1960; or 2,3-dihydroxy dioxane as described in Jefireys US. Patent 2,870,013, issued January 20, 1959.

The emulsions can contain a coating aid such as saponin; a lauryl or oleoyl monoether of polyethylene glycol as described in Knox and Davis US. Patent 2,831,- 766, issued April 22, 1958; a salt of a sulfated and alkylated polyethylene glycol ether as described in Knox and Davis US. Patent 2,719,087, issued September 27, 1955; an acylated alkyl taurine such as the sodium salt of N-oleoyl-N-methyl taurine as described in Knox, Twardokus and Davis US. Patent 2,739,891, issued March 27, 1956; the reaction product of a dianhydride of tetracarboxybutane with an alcohol or an aliphatic amine containing from 8 to 18 carbon atoms which is treated with a base, for example, the sodium salt of the monoester of tetracarboxybutane as described in Knox, Stenberg and Wilson US. Patent 2,843,487, issued July 15, 1958; a water-soluble maleopimarate or a mixture of a water-soluble maleopimarate and a substituted glutamate salt as described in Knox and Fowler US. Patent 2,823,- 123, issued February 11, 1958; an alkali metal salt of a substituted amino acid such as disodium N-(carbo-p-tert. octylphenoxypentaethoxy) glutamate, or a sulfosuccinamate such as tetrasodium N-(1,2-dicarboxyethyl-N-octadecyl sulfosuccinamate, or N-lauryl disodium sulfosuccinamate.

The sensitizing addenda of the invention can be used in various kinds of photographic emulsions. In addition to being useful in orthochromatic, panchromatic, and infrared sensitive emulsions, they are also useful in X-ray and other non-optically sensitized emulsions. They can be added to the emulsion before or after any optical sensitizing dyes which may be used. Various silver salts can be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver brornoiodide. The subject addenda can be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other colorgenerating materials, emulsions of the mixed-packet type, such as described in Godowsky US. Patent 2,698,794, issued January 4, 1955, or emulsions of the mixed-grain type, such as described in Carroll and Hanson US. Patent 2,592,243, issued April 8, 1952. Suitable color couplers usually belong to three widely known types, i.e., pyrazolone couplers, phenol couplers and open-chain ketornethylene couplers which combine with the oxidation products of aromatic primary amine silver halide developing agents to produce magenta, cyan and yellow images respectively. Development accelerators can be utilized in developing such color emulsions including polyethylene glycols, their ester derivatives, their ether derivatives typically having the formula wherein R is an alkyl radical having 1 to 5 carbon atoms and wherein n is 15l00, and related derivatives. The subject addenda can also be used in emulsions which form latent images predominantly on the surface of the silver halide crystal or in emulsions which form latent images predominantly insidethe silver halide crystal, such as those described in Davey and Knott US. Patent 2,592,250, issued April 8, 1952. V

The subject addenda can also be used in emulsions intended for use in diiTusion transfer processes which utilize the undeveloped silver halide in the non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver Such processes are described in Rott U.S. Patent 2,352,014, issued June 20, 1944, and Land US. Patents 2,584,029, issued January 29, 1952; 2,608,236, issued December 28, 1954 and 2,543,181, is sued February 27, 1951. They can also be used in color transfer processes which utilize the diffusion transfer of an imagewise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of this type are described in Land US. Patents 2,559,643, issued July 10, 1951 and 2,698,798, issued January 4, 1955; Land and Rogers Belgian Patents 554,- 933 and 554,934, granted August 12, 1957; International Polaroid Belgian Patents 554,212, granted July 16, 1957 and 554,935, granted August 12, 1957; and Yutzy U.S. Patent 2,756,142, issued July 24, 1956.

In the preparation of the silver halide dispersions employed for preparing silver halide emulsions, there can be employed as the dispersing agent for the silver halide in its preparation, gelatin or some other colloidal material such as colloidal albumin, a cellulose derivative, or a synthetic resin, for instance, a polyvinyl compound, although gelatin is preferred. Some colloids which can be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe US. Patent 2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 19-26% as described in US. Patent 2,327,808 of Lowe and Clark, issued August 24, 1943; a Water-soluble ethanolarnine cellulose acetate as described in Yutzy U.S. Patent 2,322,085, issued June 15, 1943; a polyacrylamide having a combined acrylamide content of 30-60% and a specific viscosity of 0.25-l.5 on an imidized polyacrylamide of like acrylamide content and viscosity as described in Lowe, Minsk and Kenyon US. Patent 2,541,- 474, issued February 13, 1951 zein as described in Lowe US. Patent 2,563,791, issued August 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith US. Patent 2,768,154, issued October 23, 1956; or containing cyanoacetyl groups such as the vinyl alcohol-vinyl cyanoacetate copolymer as described in Unruh, Smith and Priest US. Patent 2,808,331, issued October 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described Illingsworth, Dann and Gates U.S. Patent 2,852,382, issued September 19, 1958. If desired, compatible mixtures of two or more of these colloids can be employed for dispersing the silver halide in its preparation.

The above-described emulsions of the invention can be coated on a wide variety of supports in accordance with usual practice. Typical supports for photographic elements of the invention include cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethyleneterephthalate film and related films of resinous materials, as Well as glass, paper, wood, metals and others.

The present invention is further illustrated by the following examples of preferred embodiments thereof.

EXAMPLE 1 Typical 1,1-dirnethylhydrazinium salts were incorpo rated into a high speed negative-type gelatino-silver bromoiodide emulsion which was panchromatically sensitized with cyanine dye. The emulsion was coated on cellulose acetate film supports at a coverage of about 435 mg. of silver and about 1050 mg. of gelatin per square foot. The prepared photographic elements were exposed in the form of film strips in an Eastman lb sensitometer, developed for 5 minutes at 68 F., and then fixed, washed and dried in the usual manner. Test samples containing no 1,1-dimethylhydrazinium salt were also included in the tests for purposes of comparison.

The developer had the following formula: 1

t G. N-methyl-p-aminophenol sulfonate 2.5 Hydroquinone 2.5 Sodium sulfite (anhydrous) 30.0 Sodium borate 10.0 Potassium bromide 0.5

Water to make one liter.

Table A Cone. of Relative Addenda addenda speed 7 Fog (g./mole AgX) Control 0 100 1. 27 12 1-n-deoyl-1,l-dimethylhydrazinium perchlorate 0. 3 107 1. 27 11 D0 0. 9 118 l. 25 13 l-n-dodecyl-1,1-dimethylhydrazinium perchlorate i- 0.3 132 1. 08 Y 12 l-n-hexadeeyl-1,l-dimethylhydraziniurn perchlorate 0.8 129 0. 98 17 1-n-octadecyl-1,1-dimethylhydraziniurn perchlorate 0.3 129 0. 15

Cone. of Relative Addenda addenda speed 7 Fog (glmole AgX) Control 1. O1 13 l-n-tetradecyl-l,l-dimethylhydrazinium perchlorate 0. 3 135 1. 20 16 D0 0. 9 151 1. 13 .22 Control 0 100 1. 01 13 1,4-tetramethylenebis(1,1 dimethylhydrazinium perehlorate) 0. 75 107 1. 01 12 D0 3.0 1.04 .11 1,6-hexamethylenebis(1,1-dimethylhydraziniurn perchl0- rate) 0. 75 107 1. 01 13 D0 3.0 110 1. 00 .12

As can be observed from the data set out in Table A above, the subject 1,1-dimethylhydrazinium salts substantially increase the speed of photographic silver halide emulsions without accompanying undesirable amounts of fog.

EXAMPLE 2 described for the data in Table A. The developer used to obtain the data in Table B (Developer I) is described in Example 1, and the developer used to obtain the data in Table C (Developer 11) has the following formula:

1 G. N-methyl-p-aminophenol sulfate 2.0 Hydroquinone 8 Soditun sulfite (anhydrous) 90 Sodium carbonate monohydrate 53.5 Potassium bromide 5.0

Water to make one liter.

Table B 7 Developer I Addenda.

Cone. of Relative addenda speed Fog (gJmole AgX) Control 100 1. 1, 14-tetramethylenebis (1,1-

dimethylhydrazinium perchlorate) 0.75 120 1.01. 12 Do 3.0 132 1.01 11 1,10-decamethylenebis (1,1-

, dimothylhydrazininm perchlorate) 0.75 141 .91 13 Table C Developer II Addenda Cone. of Relative addenda speed 7 Fog (gJmoleAgX) Control 0 100 1.09 13 1,14-tetramethylonebis(1,1-

dimethylhydrazinium perchlorate) 0. 75 123 1. 61 13 Do 3.0 141 0.97 .13 1,10-decarncthylenebis(1,1-

dimethylhydrazinium perchlorate) 0.75 191 0. 92 15 The data set out in Tables B and C above further illustrate the utility of the subject 1,1-dimethylhydrazinium salts as sensitizers for photographic silver halide emulsions.

EXAMPLE 3 To illustrate the unexpectedly high sensitizing properties of the l, l-dimethylhydrazinium salts of the invention, a typical sensitized addendum of the invention was compared with several known sensitizing hydrazine salts. The various addenda were incorporated into the photographic gelatino-silver bromoiodide emulsion described in Example 1, coated on a cellulose acetate film base at a coverage of 725 mg. of silver and 1330 mg. of gelatin per square foot and exposed in an Eastman Ib sensitometer, developed for 6.5 minutes at 68 F. in a developer of essentially the same composition as described in Example 1, and then fixed, washed and dried in the usual manner.

Samples were exposed in the sensitometer both initially and after one week of incubation at 120 F. and 50% relative humidity. The results of the sensitometric tests are summarized by the data set out in Table D below. In Table D, for convenience of comparison, the sensitizer addendum of the invention, l-n-decyl-1,1-dirnethylhydrazinium perchlorate, was used as the control and was given an initial relative speed of 100. The respective addenda were utilizedat 1.5 grams of addenda per mole of silver halide in the emulsion.

Table D Original Test 1 Week at 120 F., g 50% 3.11. Addenda Rel. Fog Rel. 1 Fog speed speed l-n decyl-Ll-dimethylhydrazinium perchlorato* 100 0.76 .11 112 0.72 .12 a-Acethydrazide pyridiniumchloride 69 0. 74 .11 72 0.70 .13 g-Bcnzoylacethydrazidoyridinium chloride- 0" 61 0.71 .10 51 0. 64 .11 Acetoearbohydrazide pyridinium chloride 09 0.71 .11 74. 0.68 .13

*A sensitizer addendum oi the invention. As demonstrated by the data set out in Table D above the specific substituted hydrazinium salts of the invention are substantially superior to typical known sensitizing hydrazine derivatives.

EXAMPLE 4 The l-alkyl-l,l-dimethylhydrazinium salts used to obtain the test data set out in the above tables can be prepared by the procedure illustrated by the following equations:

wherein R is an alkyl group. More specifically, 37.5 g. of 1,1-dimethylhydrazine is dissolved in 400 ml. of diethyl ether and a 0.5 mole of the alkyl bromide is added to the solution. After 4 days at 25-30 C., 1-all 1yl-1,1-dirnethylhydraziniurn bromide is separated from the reaction mixture and converted to the perchlorate salt by dissolving in warm water and mixed with an aqueous solution of sodium perchlorate. A 10% molar excess of the sodium perchlorate is used to insure a complete reaction. In most cases the crystalline 1-alkyl-1, l-dimethylhydrazinium perchlorate separates immediately upon cooling the resulting reaction mixture, and often before cooling. Table E below summarizes analytical data for several typical sensitizer addenda of the invention prepared by the above described method.

Table E 0 Ha Q3 RN-NI-Iz 0101 1 nal sis, ercent R moiety x y p O t H l N Cl (a) n-Decyl:

Calcd 48. 2 9.1 9. 3 11. 8

Found 48. 3 9. 3 9. 4 l2. 1 (b) n-D odecyl:

Oalcd 51. 1 10. 1 8. 5 l0. 7

Found 51. 5 10.3 8. 6 10.7 (c) n-Totradecyl:

Calcd 53. 6 10.7 7. S 9. 9

Found 54. 6 10. 4 7.1 9. 8 (d) rbflexadecyl:

Calcd 58. 5 10.7 7. 2 9. 2

Found 58. 3 10. 9 6.0 9. 7 (e) n-O ctadecyl:

Calcd 59. 2 10. 9 5. 7 9. 4

Found (S0. 2 11.3 5. 3 9. 5

EXAMPLE 5 The a,w-alkylene bis(1,l-dimethylhydraziniuin salts) used to obtain the test data set out in the above tables can be prepared by the procedure illustrated by the following equations:

l H CH3 2hr 2NaClO 2010. ZNaBr ml. of diethyl ether and 1. 1 mole of LI-dimethylliydrazine. After 3 days at ZS-30 C. the alkylene bis(1,1- dimethylhydrazinium bromide) is separated and converted to the perchlorate salt by dissolving in Water and mixing with a molar excess of a 10% solution of sodium perchlorate. The resulting crystalline a,w-alkylene bis(1,1-dimethylhydrazinium perchlorate) usually separates immediately and can be recrystallized from water. Table F below summarizes analytical data for several typical sensitizer addenda of the invention prepared by the above described method.

Table F ([311 $113 $63 [Havana-Norm 20104 C H; H

Analysis, percent R moiety (a) Tetramethylcne:

Calcd 25. 6 6. 4 14. 9 18. 9 Found 25. 4 6. G 14. 9 1S. 6 (b) Hexamethylene:

Calcd 29. 8 6. 9 13. 9 17.6 29. 8 7. 1 13. 8 16. 3

Thus, the present invention provides a neW class of useful chemical sensitizers 'for photographic silver halide emulsions.

The invention "has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected Within the spirit and scope of the invention as described :hereinabove and as defined in the appended claims. 1

We claim:

1. A photographic gelatino-silver halide emulsion containing a sensitizing amount of a sensitizer having a formula selected from the group consisting of wherein R is an alkyl radical having 2 to 20 carbon atoms, R is an :alkylene radical having '2 to 20 carbon atoms and X is an anion.

2. A photographic emulsion support having coated thereon a photographic silver al-ide emulsion as described in claim 1,

3. A photographic gelatino-silver halide emulsion containing a sensitizing amount of a sensitizer having the for- 1% wherein R is an alkyl radical having 2 to 20 carbon atoms and X is an anion.

'4. A photographic gelatino-silver halide emulsion as described in claim 8 wherein X is a perchlorate anion.

15. A photographic gelatino-silver halide emulsion containing a sensitizing amount of a sensitizer having the formula wherein R is an alkylene radical having 2 to 20 carbon atoms and X is an anion.

6. A photographic gelatino-silver halide emulsion as described in claim 5 wherein X is a perchlorate anion.

7. A photographic gelatino-silver halide emulsion containing about .01 to 10 grams per mole of silver halide of 1-n-decy"l-1,l-dimethyl'hydraziniutm perchlorate.

8. A photographic gelati-no-silver halide emulsion containing about .01 to 10 grams per mole of silver halide of l-n-dodecyll,l dimethylhydrazinium perchlorate.

9. A photographic geiatino-silver halide emulsion containing about .01 to 10 grams per mole of silver halide of 1-n-tetradecyl-1,l-dirnethylhydrazinium perchlorate.

1%. A photographic gelatino-silver halide emulsion containing about .01 to 10 grams per mole of silver halide ot' l-n-hexadecyl-l,l-dimethylhydrazinium perchlorate.

11. A photographic gelatino-silver halide emulsion containing about .0 1 to 10 grams per mole of silver halide of l-n-octadccyl- 1 l-dimethylhydrazinium perchlorate.

12. A photographic gelatino-silver halide emulsion having incorporated therein a sensitizing amount of a sensitizer selected from the group consisting of l-n-decyl-1,l-dimethylhydrazinium perchlorate,

1-n-dodecyl-l,l-dimethylhydrazinium perchlorate,

l-n-tetradecyl-l,l-dimethylhydrazinium perchlorate,

l-n-hexadecyl-l, i-dimethylhydrazinium perchlorate,

-1-n-octadecyl1,l-dimethylhydrazinium perchlorate,

1,4-tetramethylene bis'(1,l-dimethylhydrazinium perchlorate),

1,6-hexametlhylene bis(1, l dimethylhy drazinium perchlorate) 1,10-decamethylene bis(1,1-dimethylhydrazinium perchlorate), and

1, l'4-tetradecamethylene bis( 1, l-dimethylhydrazinium perchlorate) References Cited by the Examiner UNITED STATES PATENTS 2,245,236 6/41 Trivelli et a1 96107 2,288,226 6/42 Carroll et al. 9 6-107 2,410,690 11/ 46 Smith et a1 96107 3,113,026 12/63 Sprung et al 96-107 NORMAN G. TORCH'IN, Primaly Examiner, 

1. A PHOTOGRAPHIC GELATINO-SILVER HALIDE EMULSION CONTAINING A SENSITIZING AMOUNT OF A SENSITIZER HAVING A FORMULA SELECTED FROM THE GROUP CONSISTING OF 